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#include <stdio.h>
#include <stdlib.h>
#include "stack.h"
/* Stack implementation is a linked list with a header */
struct node
{
elem data;
ptr_to_node next;
};
int is_empty(stack s)
{
return s->next == NULL;
}
stack create_stack()
{
stack s;
s = malloc(sizeof(struct node));
if(s == NULL)
printf("error");
make_empty(s);
return s;
}
void make_empty(stack s)
{
if(s == NULL)
printf("must create a stack first");
else
while(!is_empty(s))
pop(s);
}
void push(elem x, stack s)
{
ptr_to_node tmp;
tmp = malloc(sizeof(struct node));
if(tmp == NULL)
printf("out of space");
else {
tmp->data = x;
tmp->next = s->next;
s->next = tmp;
}
}
void pop(stack s)
{
if(!is_empty(s)) {
ptr_to_node tmp = s->next;
s->next = s->next->next;
free(tmp);
} else
printf("Empty stack");
}
elem top(stack s)
{
// if(is_empty(s))
// printf("empty stack");
// else
// return s->next->data;
//
// return -1;
//
/* tune version */
if(!is_empty(s))
return s->next->data;
printf("empty stack");
return 0;
}
void print_stack(stack s)
{
printf("--------\n");
while(!is_empty(s)) {
printf(" %d\n", s->next->data);
s = s->next;
}
printf("--------\n");
}
void test()
{
stack s;
s = create_stack();
push(1, s);
push(2, s);
print_stack(s);
push(3, s);
push(4, s);
push(5, s);
print_stack(s);
printf("%d\n",top(s));
pop(s);
print_stack(s);
pop(s);
pop(s);
pop(s);
pop(s);
pop(s);
pop(s);
print_stack(s);
}
int main()
{
test();
return 0;
}
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